Compressor shut-off valve mechanism



Patented Feb. 20, 1940 comaassoa SHUT-OFF VALVE mncnamsu Steve Schnell, seneuie.

Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application July 5, 1938, Serial No. 217,488 g 13 Claims.

My invention relates to valve mechanismand more particularly to valve mechanism for shut.-

ting off the intake of a compressor to unload it.

- Oneof the objects of my invention is to p 5 vide an improved shut-oi! valve mechanism for such association with acompressorand its receiver that the compressor intake will be automatically closed when the pressure in the receiver reaches a predetermined maximum value and automatically reopened when the pressure in the receiver drops to a predetermined minimum value.

Another object of my invention is to provide improved means for quickly relieving the. pressure acting on the movable shut-oil valve mem ber of the mechanism when the receiver pressure drops to the predetermined minimum value so that said valve member will be caused to be positively opened under the action of spring.

Still another object of my invention is to so combine and arrange the parts of the valve mechanism that they will operate in an efllcient and reliable manner.

parent from the following description taken in connection with the accompanying drawings showing two embodiments in which Figure 1 is a view showing one form of my shut-oi! valve mechanism associated with a compressor and its receiver; Figure 2 is an enlarged longitudinal cross section of the valve mechanism showin details thereof; Figure 3 is an enlarged longitudinal cross-sectional viewof a modified construction; and Figure 4 is'a left-hand end view of the/ valve mechanism shown in Figure :1.

Referring to the drawings in detail, the air compressor I, with which I have illustrated my shut-oil valve mechanism as being associated, is of the rotary type having a stator 2 and an eccentricallymounted rotor 3 providedwith a plurality of blades" 4 '(one only being shown). The stator has an intake port 5 and an outlet'port 6, the latter openinginto an oil dome l which is connected to a pressure tank 8 by means of a conduit 9, the oil dome and the pressure tank both being considered as parts of the receiver of the compressor. The outlet of the compressor has associated therewith acheck valve III for preventing back flow of compressed fluid and the outlet of the dome is controlled by another check valve II. The pressure tank 8 is adapted to be connected by a conduit II with any suitable fluid pressure-actuated system v(not shown) which its biasing Other objects of my invention will become ap compressing fluid after the fluid in the receiver has been placed under a predetermined maximum pressure; This is best accomplished by shutting oil the intake port so the air or other fluid which is being compressed by the 'compr'esl0 sor is not permitted to enter the compressing chamber. It is also desirable that the intake port not only be automatically closed at the proper time but that it also be reopened whenever the pressure in the receiver drops.

In accordance with my invention, I have provided an improved valve mechanism l3 which is associated with the compressor intake and also with the compressor oil dome and the receiver wherebythe desired operation of the valve mechanism is accomplished; The valve mechanismcomprises a casing l4 secured to the compressor by an attaching flange IS. The casing is provided with a cylindrical bore i6 and this bore is connected to the compressor intake by a passage I1. 'The inlet passage l8 for the bore is associated with-an air cleaner I9 for cleaning the incoming air. Within bore I6 is a slidable valve member 20 carrying a rubber member 2| for cooperation with a seat 22 in the bore for clos- 0 ing ofl communication between passages l1 and I8. The forward end of the piston is sealed by a packing cup 23 in order to prevent leakage of fluid from chamber 24 closed by a plug 25. Associated with the forward end of the piston within chamber 24 is a valve element 26 mounted on a tubular projection 21 and this valve element is adapted to cooperate with a rubber seat 28 to prevent communication from chamber 24 to a passage 29 in plug 25 leading to a chamber 30. the passage being aligned with the tubular member 21. The slidable valve member 20 is formed with a bore 3| also communicating with the tubular projection'2l and within this bore. is a plunger 32 having a projecting rod 33recip1'ocably mounted in'the nut 34 threaded'in the right end wall of the casing. The plunger '18 formed with a flange 32' for engaging the rubber member 2| to seal the plunger in bore ll. A spring 35 surrounds rod 33 and is interposed between plunger 32 and nut 34 in order to bias flange 32' of the plunger against the valve member 20 and valve member 20 to a position where the valve member is 'unseated. The spring ll 5 desired pressure in. the receiver. {For the pur-' also normally maintains the valve element 26 in engagement with seat 26.

Within chamber 36 of plug is a plunger 36,. the right end of which carries a valve element 31 for closing passage 29. Associated with the plunger is a-diaphragm 36 for preventing communication from a chamber 33 to chaniber 36. 1

the former communicating with a passage 46 connected to a conduit 4| leading from the pressure tank 8 of the compressor. The plunger 36 is acted upon by a spring 42 for maintaining the valve element 31 unseated and the left end of the plungerin engagement with the surface surroundingthe opening 46. The plug 25 is formed with a suitable outlet passage 43 for placing chamber 36 in communication with the atmosphere. 7 a

The chamber 24 is connected to the oil dome 1 of the compressor in order that the forward end of valve member26 may at all times be subiect to the pressure of the fluid in the dome smallerthan passage 29.

The valve mechanism may be set to automat ically shut off the compressor intake at any pose of this description it is assumed that the maximum pressure desired in the receiver is one I hundred pounds per square inch. The spring'35 under these conditions is adjusted by nut 34 to prevent valve member 26 from being moved to closed position except when the pressure in chamber 24 is slightly greater than one hundred pounds per square inch.- Such a setting of the spring will permit plunger 32 to be moved relative to valve member 26 when the pressure in bore 3| is about seventy-five pounds per square inch, the area of theplunger acted upon by this pressure being less than the area of the valve element which is acted uponby. the pressure in chamber 24. Spring 42 for plunger 36 is of. such strength that the plunger will not be moved to closed position until the pressure in chamber 39 is approximately ninety pounds per square inch.

With the compressor'operating and the valve parts in the position shown in Figure 2, air will be free to enter the compressor and be forced out into the oil dome and into tank 8. When the pressure in the receiver reaches the value of ninety pounds per square inch, plunger 36 will be moved to the right and passage 29 closed by valve element 31. Continued operation of the compressor will bring the pressure in the oil dome and the tank up to one hundred pounds per square inch. When this pressure is reached, there will also be one hundred pounds per square inch pressure in chamber 24. This will be suflicient to overcome spring and move valvemember 26 to the right toward closed position. As soon as valve member 26 is moved, it will unseat valve ement 26, thereby permitting fluid under one h dred pounds per square inch pressure to; enter the passage of the tubular projection 21 and bore 31 and become efiective upon plunger 32 in addition to the end surface of valve element 26. The flange 32' of the plunger will now be moved away from the rubber member 2| after the-valve member has become seated. This will result in the pressure in chamber 24 dropping to a value of seventy-five pounds per square inch which is suflicient to hold the valve chamber 24 also results in'a drop in pressure in the compressor dome which is desirableas it relieves pressure on the oil tending to force it into the compressor which is undesirable whenthe compressor is idling. It is to be noted that the valve member, after it has initially moved and unseated valve element 26, permits additional --used therefrom, spring 42 will become effective to move plunger 36 to the left and unseat valve I element 31. This will immediatelycause a release of pressure in chamber 24 through passage 26, chamber 36 and outlet passage 43 since passage 29 is larger than passage 45 and, therefore, the fluid under pressure in chamber 24 will escape faster than the fluid under pressure being supplied through passage 45. The spring 35 will now become operative to move valve member 26 to the left away from seat 22 and reopen the intake of the compressor to atmosphere by way of passages I1 and I6. The parts of the valve mechanism will now assume the position shown in Figure 2 and the compressor will again build up the pressure in the dome and the tank to the desired maximum pressure of one hundred pounds per square inch wherein the valve mechanism will again function in a manner already described to shut off the com- Dresser.

It'is to be noted that the valve mechanism is so constructed that there will be a rapid closingmovement of valve member 26 once it is initially moved by the maximum pressure in the oil dome. It is also to be noted that as soon as the pressure in the tank drops to a predetermined minimum value of ninety pounds per square inch; the pressure acting upon valve member 26 to shut off the compressor is immediately relieved and the spring is eflective to immediately fully open the compressor to atmosphere. In the arrangement of the-parts shown there is no possibility of valve member 26 "fluttering" on and 0d its seat 22. Once the valve element is seated, it wiH remain so and will not become unseated until the domepressure drops to the minimum value of ninety pounds per square inch. When this pressure is reached, the pressure tending to hold the valve seated will be immediately exhausted to atmosphere and the valve member quickly and posi-' tively moved to its open position. I

In the construction shown in Figures 3 and4, the valve casing 41 is provided with a chamber 48 which is connected by a passage 49 through the attaching flange 49' to the intake oi the compressor and a passage 56 in a fitting member 56' to the atmosphere through the air cleaner.

Within chamber 46 is a valve seat 5| for cooperation with the movable valve member 52 for closing ofl communication from the atmosphere to the intake of the compressor. The valve member is biased to its open position against a stop 53 by a spring 54. The forward end of the piston has associated therewith a sealing cup 55 and at theiend' of this piston is a chamber 56.

- The right-handend of the casing is formed with a bore 51 having a reduced portion 58 communicating with chamber 56 by means of passage 56. Slidable in bore 51 is a piston 66 having a portion projecting into the small bore ,56 with which is associated a sealing cup 6|. The piston is backed by a spring 62 which normally maintains the piston against shoulder 63. The

ried by the piston and the end oi this sleeve I is so related to the head of the plunger that the plunger will not be moved with the piston 60 until the piston has moved a predetermined distance to the right. When the plunger is picked up by the piston, it will unseat valve element 68.

The small bore 58 communicates with a conduit II which is connected the compressor.

The casing is also provided with an additional to the receiver of bore 12 which communicates with chamber ll left against seat SI.

and with an atmospheric port I3 by means of a passage 14. Within the bore is a valve element "biased by a spring 16 toward the position to close the passage. The valve element isformed with a stem 11 which is adapted to be engaged by the piston 80 when it is against the shoulder 63 to thereby maintain thevalve element un-,

seated.

With the parts in the position shown, air is free to enter the compressor by way of passages 50 and 49. when the pressure in the receiver reaches one hundred pounds per square inch, the pressure acting against the end of piston 60 will be suflicient to overcome spring 62 and move the piston to the right. When piston 80 moves to the right, the valve element 15 will first be seated and then valve element 88 unseated. The chamber 56 will now be closed oil from communication with the atmosphere and connected to the receiver, and the pressure in the chamber will be suflicient to move the valve member 52 to the The compressor will now be shut oii from the atmosphere and will run under no load.

When the pressure in the receiver drops to a predetermined value, say ninety pounds per square inch, spring 82 will be strong enough to i move piston 60 to the left. .This will first cause valve element 68 to become seated and close of! communication between chamber 55 and the receiver. As the piston continues to move to the 1eit, 'vaive element I5 will be unseated by the piston engaging stem 11. The fluid pressure in chamber 58 will now be exhausted to atmosphere through passage I3 and spring 54 will then be effective to quickly unseat the valve member 52. Pressure may now be built up in the receiver'to the maximum value of one hundred pounds per square inch and the valve mechanism will again operate to shut off the compressor. w

Being aware of the possibility of modification in the particular structure herein described with-- acted upon by mild pressure from the receiver for closing the port, a spring for biasing the.

member to open position and preventing movement of the member to closed position except when acted upon by a predetermined pressure, means comprising the movable member and a portion of the casing within which it reciprocates for forming a chamber, conduit means in the easing for connecting the chamber to the receiver, means including a passage for connecting the chamber to atmosphere independently of the conduit means, a valve for controlling said passage, .and means operable by pressure from the receiver 101 closing said last named valve.

2. In a unitary valve mechanism of the class described for association with the intake of a compressor and the fluid pressure receiver therefor, a casing having a port for communication with the compressor intake, a movable member reciprocable in said casing andadapted to be acted upon by fluid pressure from the receiver for closing the port, a spring for biasing the member to open position and preventing movement of the member to closedposition except when acted upon by a predetermined pressure, means comprising the movable member and a portion of the casing within which it reciprocates for forming a chamber, conduit means in the casing for connecting the chamber to the receiver, means including a passage for connecting the chamber to atmosphere independently of the conduit means, a valve for controlling said passage, and means comprising a spring for callsing said valve to be opened when the pressure in the receiver drops a given amount below the predetermined pressure required to move the movable member.

3. In vazve mechanism of the class described for association with a compressor and a receiver connected to the exhaust side thereof, a casing the receiver for closing said valve when the pres--. sure'therein is less than the pressure necessary to move the movable valve'member to close the port associated with the intake of the compressor. v

4. In valve mechanismpf the class described for association with a'compressor and its receiver, a casing having a port for communication with the intake of the compressor, a mov-' able valve member in said casing for controlling the port, a spring for biasing the member to open 1 position, said member forming a movable wall of a chamber which is adapted to be connected tothe receiver, means operable by fluid pressure from thereceiver for moving said valve, member against said spring to'closed position, said means comprising a surface of said valve member acted upon by. a predetermined pressureirom the receiver to initially move the valve member toward c'osed position, means operable upon initial movement of the valve member. for causing an additional. surface of the valve member to be acted upon by said predetermined pressure, meansforming a relief, passage from the chamber, a 7| for association with a compressor and its receiver, a

a casing having a port for communication with the intakeof the compressor, a movable valve member in said casing for controlling the port, a spring for biasing the member to open position, said member forming a movable wall or a" chamber which is adapted to be connected to the receiver, -means-operable by fluid pressure irom ward closed position.

the receiver for moving said valve member against said spring to closed position, said means comprising. a surface of said valve member acted upon by a predetermined pressure from the receiver to initially move the valve member toward closed position, means operable upon initial movement of the valve member for causing an additional surface of the valve member "to be acted upon by said predetermined pressure, means forming a relief passage from the, chamber, a valve for said passage, a spring for biasing the valve open, and means for maintaining said valve closed against the bias of its spring by a fluid pressure from the receiver which is of lower value than the predetermined pressure, whereby the relief passage from the chamber will be closed prior to any movement of the valve 'member to- 6. In valve mechanism of the class described for association with a compressor and its receiver, a

' casing having a port for communication with the intake of the compressor, a movable valve member in said casing for controlling the port, a spring for biasing the member to open position, means comprising a portion of the movable valve mem ber and the casing for forming a'chamber which is adapted to be connected to the fluid pressure receiver, means comprising another portion ofthe valve member for forming a second chamber, vave means for connecting the second chamber to the first chamber when said movable valve member is initially moved toward closed position by a predetermined pressure, means forming a relief passage from the chambers, a valve for said passage, a springfor biasing the valve open, and means for maintaining the valve closed against the bias of itsspring byfluid pressure from the receiver which is of lower value than the value of the predetermined pressure, whereby the relief passage will, be closed prior to the movement of the valve means to connect the two chambers.

'7. In valve mechanism of the class described for association with a compressor and its receiver, a casing having a port for communication with the intake of the compressor, a movable valve member in said casing for controlling the port, a

a spring for biasing the member to open position, means for moving said movable valve member to closed position by a predetermined pressure from the receiver, andv means for causing said spring to exert less force on the valve member tending to bias the valve member'to open position after the valve member is moved to closed position.

8. In valve mechanism of the class described for association with a compressor having an oil dome and a pressure tank connected to the exhaust side of the compressor and a check valve for preventing return flow of fluid from the tank to the oil dome, a casing having a port for communication with the intake of the compressor, a movable valve member in said casing for controlling the port, a spring for biasing the member to open position, means for moving said movable valve member to closed position by a predetermined pressure from the oil dome, and means operable when the valve member 'is in closed position for permitting a drop in the pressure in the oil dome.

. 9. In valve mechanism of the class described for association with'a compressor having an oil dome and a pressure tank connected to the exhaust side of the compressor-and a check valve 10. In valve mechanism of the class described for association with a compr'essor having an oil dome and a pressure tank connected to the e'xhaust'side of the compressor and a check valve for preventing return flow of fluid from the tank to the oil dome, a casing having a port for communication with the intake'of the compressor, a movable valve member in said casing for controllingthe port, a spring for biasing the member to open position, means comprising a portion of the movable valve member and the casing for forming a chamber which is adapted to be connected to the oil dome, means comprising another portion of the'valve member for forming a second chamber, valve means for connecting the second chamber to theiirst chamber when said movable valve member is initially moved toward closedposition .by a predetermined pressure, and relief valve means including a movable element carried by the movable valve member and associated with the spring thereof, said movable element being movable'against the bias of the spring' and by the fluid pressure in the chambers after the movable valve member is closed to thereby permit a reduction in pressure of the fluid in thechambers and the dome.

11. In valve mechanism of the class described for association with a compressor and itsreceiver, a casing having a port for communication with the intake of the'compressor, a movable valve member in said casing for controlling the port, a spring for biasing the member to open position, said member forming the movable wall of a chamber, a conduit for connecting the chamber with the receiver, a valve for controlling said conduit, a second conduit for connecting the chamber with the'atmosphere, a valve for the last named conduit, and means operable by a predetermined pressureirom the receiver for permitting the last named valve to be closed anda springforbiasing the member to open position,-

said member forming the movable wall of a chamber, means comprising a movable member for forming a second chamber adapted to becon- 15 nected with the receiver, a spring acting on the movable member in the second chamber. a conduit connecting the chambers, a valve for controlling the conduit, means operable by a predetermined fluid pressure in the second chamber for causing the movable member therein to move said valve to open position, means forming a relief passage for the first chamber, a valve for said passage, a spring for biasing said valve closed, and means for causing said last named valve to be held open against the bias of its spring 'by the movable member in the second chamber when it is in a position permitting said first named valve to be closed'.

13. In valve mechanism oi the class described for association with a compressor and its receiver, a casing having a. port for communication with the intake of the compressor, a movable valve member in said casing for controlling the port, a spring for biasing the member to open positiomsaid member forming the movable wall of a chamber, a conduit for connecting the chamber with the receiver, a valve for said conduit, a conduit for connecting the chamber with the atmosphere, a valve for the last named conduit, a movable member subject to fluid pressure from the .receiver, a spring for biasing said member against the action of the pressure, and'means operable by the movement of the movable member against its spring for first permitting the second valve to close and subsequently opening the first valve.

' STEVE SCHNELL. 

